aesEncrypt 产生不同的结果

Question

我正在尝试在 Swift 3 中加密一个字符串，而我的加密每次都给出不同的输出。这是为什么？ （我在python中尝试过类似的加密，加密后的输出总是一样的）。

这是我的 Swift 3 aesEncrypt 函数：

func aesEncrypt(key:String, iv:Array<Any>, options:Int = kCCOptionPKCS7Padding) -> String? {
    if let keyData = sha256(string:key),
        let data = self.data(using: String.Encoding.utf8),
        let cryptData    = NSMutableData(length: Int((data.count)) + kCCBlockSizeAES128) {

        let keyLength              = size_t(kCCKeySizeAES128)
        let operation: CCOperation = UInt32(kCCEncrypt)
        let algorithm:  CCAlgorithm = UInt32(kCCAlgorithmAES128)
        let options:   CCOptions   = UInt32(options)

        var numBytesEncrypted :size_t = 0

        let cryptStatus = CCCrypt(operation,
                                  algorithm,
                                  options,
                                  (keyData as NSData).bytes, keyLength,
                                  iv,
                                  (data as NSData).bytes, data.count,
                                  cryptData.mutableBytes, cryptData.length,
                                  &numBytesEncrypted)
        // ADDED PRINT STATEMENTS 
        print("keyData")
        print(keyData)
        print("\(keyData as NSData)")
        print("iv")
        print(iv)
        var hex_iv = toHexString(arr: iv as! [UInt8])
        print(hex_iv)
        print("data")
        print(data)
        print("\(data as NSData)")

        print("encryption: cryptdata")
        print(cryptData)

        print("encryption: num bytes encrypted")
        print(numBytesEncrypted)

        if UInt32(cryptStatus) == UInt32(kCCSuccess) {
            cryptData.length = Int(numBytesEncrypted)
            let base64cryptString = cryptData.base64EncodedString(options: .lineLength64Characters)
            return base64cryptString
        }
        else {
            return nil
        }
    }
    return nil
}

当我尝试使用 initial_string = "hello" 运行以下代码时，我每次都会得到不同的加密输出字符串。

let iv [UInt8](repeating: 0, count: 16)
let key = "sample_key"
let initial_string = "hello"

let encryptedString = initial_string.aesEncrypt(key: key, iv: iv)
print("Encrypted string")
print(encryptedString)

第一次运行带有“hello”字符串的代码的示例输出：

keyData
32 bytes
<d5a78c66 e9b3ed40 b3a92480 c732527f 1a919fdc f68957d2 b7e9218f 6221085d>
iv
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
data
5 bytes
<68656c6c 6f>
encryption: cryptdata
<b17d67fc 26e3f316 6a2bdfbf 9d387c2d 00000000 00>
encryption: num bytes encrypted
16
Encrypted string
Optional("sX1n/Cbj8xZqK9+/nTh8LQ==")

第二次使用“hello”字符串运行代码的示例输出：

keyData
32 bytes
<d5a78c66 e9b3ed40 b3a92480 c732527f 1a919fdc f68957d2 b7e9218f 6221085d>
iv
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
data
5 bytes
<68656c6c 6f>
encryption: cryptdata
<01b9f69b 45deb31d eda46c2d dc9ad9e8 00000000 00>
encryption: num bytes encrypted
16
Encrypted string
Optional("Abn2m0Xesx3tpGwt3JrZ6A==")

你能告诉我为什么每次对于同一个键、iv 和字符串的输出都不同吗？谢谢！

Answer 1

免责声明：我无法运行问题代码。除其他外，它不完整，缺少扩展声明。也好像是 Swift 2 的代码，至少需要更新到 Swift 3。

加密：加密数据

完全错误，甚至是错误的长度加密数据将是块大小的倍数。

使用 PKCS#7 填充和 CBC 模式，加密结果应为：C99A30D8DA44968418E8B66F42790216。见 Cyyptomathic AES CALCULATOR。注意0b0b0b0b0b0b0b0b0b0b0b 是 PKCS#7 填充。

这是 Swift 3 中的示例，这是不是生产代码，它至少缺少错误处理。

func SHA256(string:String) -> Data {
    let data = string.data(using:.utf8)!
    var hashData = Data(count: Int(CC_SHA256_DIGEST_LENGTH))

    _ = hashData.withUnsafeMutableBytes {digestBytes in
        data.withUnsafeBytes {messageBytes in
            CC_SHA256(messageBytes, CC_LONG(data.count), digestBytes)
        }
    }
    return hashData
}

func aesCBCEncrypt(data:Data, keyData:Data, ivData:Data) -> Data {
    let cryptLength = size_t(kCCBlockSizeAES128 + data.count + kCCBlockSizeAES128)
    var cryptData   = Data(count:cryptLength)
    var numBytesEncrypted :size_t = 0

    let cryptStatus = cryptData.withUnsafeMutableBytes {cryptBytes in
        data.withUnsafeBytes {dataBytes in
            keyData.withUnsafeBytes {keyBytes in
                ivData.withUnsafeBytes {ivBytes in
                    CCCrypt(CCOperation(kCCEncrypt),
                            CCAlgorithm(kCCAlgorithmAES),
                            CCOptions(kCCOptionPKCS7Padding),
                            keyBytes, keyData.count,
                            ivBytes,
                            dataBytes, data.count,
                            cryptBytes, cryptLength,
                            &numBytesEncrypted)
                }}}}

    cryptData.count = (cryptStatus == kCCSuccess) ? numBytesEncrypted : 0

    return cryptData;
}


let keyString = "sample_key"
let keyData = SHA256(string:keyString)
print("keyString: \(keyString)")
print("keyData:   \(hexEncode(keyData))")

let clearData = hexDecode("68656c6c6f")
// let keyData   = hexDecode("d5a78c66e9b3ed40b3a92480c732527f1a919fdcf68957d2b7e9218f6221085d")
let ivData    = hexDecode("00000000000000000000000000000000")

print("clearData: \(hexEncode(clearData))")
print("keyData:   \(hexEncode(keyData))")
print("ivData:    \(hexEncode(ivData))")

let cryptData = aesCBCEncrypt(data:clearData, keyData:keyData, ivData:ivData)
print("cryptData: \(hexEncode(cryptData))")

输出：

键字符串：sample_key 关键数据：d5a78c66e9b3ed40b3a92480c732527f1a919fdcf68957d2b7e9218f6221085d 清除数据：68656c6c6f 关键数据：d5a78c66e9b3ed40b3a92480c732527f1a919fdcf68957d2b7e9218f6221085d ivData：000000000000000000000000000000000 加密数据：c99a30d8da44968418e8b66f42790216

Answer 2

你看到那个 IV 了吗？那是初始化向量，它充当计数器，使您的加密每次都不同，使其更加安全且难以破解。所以基本上你的代码工作正常，但要正确解密，接收者不能仅仅通过拥有 Key 来行动，还需要 IV